Compositions and Methods for Removing Organic Substances

ABSTRACT

Compositions and methods useful for the removal of organic substances from substrates, for example, electronic device substrates such as microelectronic wafers or flat panel displays, are provided. A method is presented which applies a minimum volume of the composition as a coating to the inorganic substrate whereby sufficient heat is added and immediately rinsed with water to achieve complete removal. These compositions and methods are particularly suitable for removing and completely dissolving photoresists of the positive and negative varieties as well as thermoset polymers from electronic devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/346,877 filed Jan. 10, 2012, which was a Divisional of U.S. patentapplication Ser. No. 12/413,085 filed Mar. 27, 2009, which are herebyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the removal of organicsubstances from a substrate. In particular, the present inventionrelates to a universal method with a range of compositions, whichapplies to the removal of both amorphous and thermoset polymers fromelectronic devices such as semiconductor wafers and flat panel displays(FPD), and other microelectronic substrates.

BACKGROUND

Various polymers are used in the manufacture of electronic devices, toinclude photoresists and organic-based dielectrics. Photoresists, forexample, are used throughout semiconductor device fabrication inphotolithographic operations. The resist is exposed to actinic radiationthrough a photomask. Where a positive-acting resist is used, exposurecauses a chemical reaction within the material resulting in a solubilityincrease in aqueous alkali, allowing it to be dissolved and rinsed awaywith developer. In the case of a negative-acting material, crosslinkingof the polymer occurs in the exposed regions while leaving unexposedregions unchanged. The unexposed regions are subject to dissolution andrinsing by a suitable developer chemistry. Following development, aresist mask is left behind. The design and geometry of the resist maskis dependent upon the positive or negative tone of the resist; positivetone resist will match the design of the photomask, while a negativetone resist will provide a pattern that is opposite the photomaskdesign. The use of photoresists requires several cleaning steps with afinal clean of the mask before the next circuit design process step isimplemented.

Organic-based dielectrics represent engineering polymers used to offerinsulative properties to the microelectronic circuit. Examples of thesechemistries include polyimide (PI) andpoly-(p-phenylene-2,6-benzobisoxazole) (PBO) as manufactured byHitachi-DuPont Microsystems. Another popular organic insulator forelectronic applications is bisbenzocyclobutene (BCB), manufactured bythe USA-based, Dow Chemical Company. These polymers are applied to thesubstrate in a similar fashion as photoresists using conventional spin,spray, or they may be slit-coated as is common practice in manufacturingFPDs. For these application reasons, organic-based dielectrics may oftenbe referred to as spin-on dielectrics. Once the polymer is applied, theymay undergo a patterning process, but ultimately all of these systemslead to a final-stage cure, which permanently fixes the material inplace by undergoing chemical and physical property changes. The finalmaterial exhibits both electrical and physical properties desirable forperformance of the electric circuit. Once these organic-baseddielectrics are fully cured, they are considered to be permanent,whereby, the need for rework would either require the use of aggressivematerials such as strong acids or bases that likely would attack thesubstrate or adjacent metals or more practically, the rework conditionwould be considered as not commercially available.

Positive photoresists are commonly based upon resins of the novolac orpolyhydroxystyrene (Phost) varieties chosen for high-resolution deviceprocessing in front-end semiconductor and flat panel displaymanufacturing. Positive-tone systems represent the largest volumeportion of photoresists produced globally and there are many suppliers.Example suppliers of these systems for both semiconductor and FPDinclude the USA-based AZ Electronic Materials, the USA-based Rohm andHaas Corporation, and the Japanese company, Tokyo Ohka Kogyo Co Ltd. Inpositive photoresist applications, a substrate is etched by plasmaprocesses, which use gases of inert and chemical varieties to produceboth ionized and reactive species that travel through the mask and etchdown into the substrate. During etching, ionized and reactive speciescombine with atoms of the substrate, form a by-product, and thatby-product is vented away via the reduced pressure of the plasma system.These same gaseous species also impact the photoresist mask, baking itinto place and also ejecting carbon-containing by-products into theplasma. Photoresist by-products mix with other species in the plasma andare continually directed down towards the substrate. These materialscondense to form a residue along the sidewalls of the etched features,producing a desirable condition, otherwise referred to as anisotropicetching whereby species are highly controlled and directed into thesubstrate with little or no lateral loss. Upon completion, it is desiredto remove this etch residue along with the resist mask, as they can havedeleterious effects on subsequent processes and lead to reduced deviceperformance or device failure. Such residues and their associated resistmasks, however, can be difficult to remove, normally involving the useof formulated stripper chemistries.

Negative photoresists are commonly chosen for more rigorous processconditions whereby more aggressive chemical or thermal exposureprocesses may be used. These negative photoresists include isoprene(rubber), acrylic, and epoxy-based resins. Cyclized isoprene (rubber)photoresists are chosen for their high chemical resistance. Examples ofthese photoresists may be obtained from Fujifilm Electronic Materials,Ltd. under the trade name SC-Resist or HNR-Resist. Negative-toneisoprene resin resists are common in aluminum processing where a briefchemical etch is used to remove metal surrounding the masked feature.Negative-tone acrylic photoresists are commonly chosen forwafer-level-packaging bump formation. Suppliers include the USA-basedPrinted Circuits Division of E. I. duPont de Nemours and Company underthe trade name Riston, and the Japan's JSR Corporation for dry-film andspin-on (wet) negative acrylics, respectively. Dry-film and spin-onacrylics offer an ability to deposit thick layers from 25 to 120 microns(um), used to pattern the corresponding solder bumps. Once the patternis formed, metal deposition occurs by electroplating or screen-printing,a process that exposes the resist to heated acid or baking in excess of250° C., respectively. Another popular negative resist, an epoxy systemunder the trade name of SU-8™, originally developed by InternationalBusiness Machines (IBM) and now sold by the USA company, MicroChemCorporation, and Gersteltec Engineering Solutions, a Swiss-basedcompany. The SU-8™ is commonly chosen for thick patterns that may exceed300 microns (um), with a high-aspect ratio (i.e. height vs width), andwith the pattern definition to exhibit extremely straight sidewalls.Because of the extremely unique characteristics of the SU-8™ epoxyresin, photoresists of this variety are chosen to manufacture largedevices, and most commonly include microeletromechanical systems (MEMS).The varieties of negative-tone photoresists are significantly differentfrom positive, their cleaning (removal) practice is even more rigorous.In fact, it is commonly understood that SU-8™ photoresist is consideredto be a permanent system, removed only with more complex, time, andcostly practices.

As with any process involving photolithography, it is desirable tocompletely remove the photoresist from the substrate in order to proceedsuccessfully to the next process. Incomplete stripping of thephotoresist can result in irregularities during the next etching ordeposition step, which may cause quality and yield problems. Forexample, during solder bumping, resist contamination can prevent metalsolder from wetting to a metal pad during the board assembly reflowprocesses, resulting in yield loss in a finished assembly. The samephotoresist contamination is manifested as organic contamination infront end of line device patterning and results in the exact samenon-wetting problems in an etch or deposition process. Suchirregularities, no matter how small, continue to magnify the problemthroughout manufacturing until during final device assembly and testing,the condition leads to poor mechanical and electrical contacts, whichproduce high resistance and heat, or worse, catastrophic electricalshorting.

Throughout each of these chemical processes, one can appreciate maximumselectivity in cleanliness and high throughput must be met withoutfailure. Any problems associated with a lack of performance, presence ofresidue, or worse, a rise in process complexity, all will result inreduced yield and increased cost.

It is generally understood that the chemistry of positive tone resistsare typically hydrophilic (polar) and amorphous (i.e. non thermoset andcross-linked), and it is for these reasons that these systems arebelieved to be easier to clean (remove) using conventional solventsand/or chemical strippers. The resins for positive-tone chemistries arebased upon either novolac (cresol, phenol-formaldehyde) orpolyhydroxystyrene (PHost), with occasional options of styrenatedcopolymer and/or acrylic/PMMA (polymethylmethacrylate). Thesechemistries offer good adhesion and fixing to a wide variety of surfaceswhile the hydroxyl groups present in the various forms of novolac (i.e.cresol, bis-phenol, etc.) provide intermolecular hydrogen bonding whichaids in aqueous solubility. This condition combines during thephotoconversion of the initiator diazonaphthoquinone (DNQ) in novolacsystems, while in PHost systems, the acid catalyzed de-protection of theester forms the more soluble alcohol. When used during normal operatingconditions up to and including 100 degrees C., these systems remainsoluble in polar solvents while their UV-exposure will producecounterparts that are soluble in aqueous-base.

As indicated here, the positive-tone resists are used as primary imagingmasks for plasma-based etching. During this process, species in theplasma produce etch residue while exposing the mask to temperaturesexceeding 150 degrees C. It is well known that etch residue (e.g. sidewall polymer) is comprised of by-products of the plasma with organicconstituents of photoresist. The chemistry of the residue may compriseconstituents of the substrate, metal topography, and plasma gases, toinclude silicon, gallium, arsenic, boron, phosphate, titantium,tantalum, tungsten, copper, nickel, aluminum, chromium, fluorine,chlorine, as well as carbon containing compounds. In novolac systemswhich contain hydroxyl constituents, these elevated temperature exposureconditions will facilitate further reactions to form insoluble species.Such reactivity of hydroxyl groups with halides and active metals,especially in the heated and acidic conditions of a plasma, to producealkyl halides, esters, and, in some cases, high molecular weightpolymers is known (Morrison, R. T. and Boyd, R. N., Organic Chemistry,3rd Ed., Allyn & Bacon, Inc., Boston Mass., Ch. 16 (1973)). Conventionalcleaning of etch residue and overexposed photoresist masks resultingfrom the effects of hot plasma etching require the use of chemicalstrippers processed at elevated temperatures for extended periods oftime dependent upon the process and tool.

Typical measurement used to predict stripping challenges of bulk resinsincludes thermal analysis determination of glass transition (Tg).Relatively unchanged Tg values are observed in positive-tonephotoresists and similar amorphous systems (Fedynyshyn, T. et al., Proc.SPIE 6519, 65197-1 (2007)). Detectable increases of Tg in photoresistshave been observed to be a function of the evaporative loss in solvent,which in turn, will depend upon the thickness of the photoresistcoating. Most notable are observed increases in Tg with radiation andthermal exposure with polymer crosslinking (J. D. D'Amour et al., Proc.SPIE 5039, 966 (2003)). Such crosslinking of high temperature exposednovolac resins and negative-tone systems is consistent with the presenceof higher molecular weight species as detectable by increased values ofTg.

Cleaning (removal) of photoresist etch residue and the mask use complexchemical strippers composed of organic solvents, amines, water, reducingagents, chelating agents, corrosion inhibitors, and surfactants. Thereducing agent, hydroxylamine, has been cited extensively in theliterature as a basic material which facilitates dissolution ofphotoresist and its residue while offering protection of underlyingaluminum metal features. Common practice in using stripper chemistriesinvolves delivery of large volumes of stripper to the substrate to becleaned at a specific temperature for a given period of time.

As the industry continues to replace aluminum with copper to captureimproved performance in their devices, the stripper chemistries mustalso be adjusted. Hydroxylamine may be acceptable for cleaning ofaluminum devices; however, it is too aggressive for copper. Devicearchitecture using copper and low-K (dielectric constant, K), e.g.Cu/Low-K, require fluorinated-based chemistries to remove silicon-ladenetch residue. Amines and ammonia compounds are known to be complexingagents for Cu and are observed to etch (attack) copper metal.Additionally, fluorinated and glycol-based stripper chemistries areconsidered toxic and exhibit elevated viscosities.

Negative photoresists used in forming wafer bumping metallization masksgenerally include acrylic, styrenic, maleic anhydride or relatedmonomers and copolymers. Such materials are used to producephotosensitive thick films. These photoresists are commonly referred toas “acrylic” polymer systems due to the pendant groups on the mainpolymer chains, which include vinyl groups common to acrylics. Ingeneral, the dry-film form of acrylic photoresists is chosen whereexposure to rigorous process conditions is required. As a result of thisexposure, the cleaning of dry-film masks and residues presents astripper challenge. When a dry-film system is removed, the material istypically not dissolved. Rather, many chemical strippers interact withthe material to cause lifting or peeling from the substrate, resultingin the generation of suspended insoluble flakes and particles. Suchinsoluble materials can lead to filter fouling and performancedegradation in the processing tool. This can create a significant lossin productivity as a result of process tool downtime for maintenance. Inaddition, the failure to filter off or rinse away particles may resultin the formation of residue on the final product and contribute to yieldloss.

Resist stripping compositions that include aromatic quaternary ammoniumhydroxide such as benzyltrimethylammonium hydroxide (BTMAH), a solventsuch as an alkylsulfoxide, a glycol and a corrosion inhibitor andnon-ionic surfactant do not completely remove many dry-film resists froma wafer surface. Similarly, compositions which use pyrrolidone-basedsolvents such as N-methylpyrrolidone (NMP) exhibit the same drawback inthat they cannot achieve complete removal of many dry-film resists. Ingeneral, compositions which include a quaternary ammonium hydroxide astetramethylammonium hydroxide (TMAH) in NMP do not completely dissolvemany dry-film resist. As discussed above, incomplete dissolutionproduces particles that can become a source of contamination resultingin yield loss.

Similar experience is noted for negative-tone photoresist of therubber-based resin variety. Stripper chemistries used to clean residueand masks resulting from rubber photoresists include a hydrocarbonsolvent and an acid, commonly a sulfonic acid. High acidity is requiredfor performance and emulsification of hydrolyzed rubber components.Representative inhibitors include mercaptobenzotriazole (MBT) andrelated triazoles to prohibit attack upon adjacent metallic features. Acommon inhibitor for these chemistries includes catachol, a toxic andcarcinogenic material. Further, rinse steps for hydrocarbon strippers ofthis variety must use isopropanol (IPA) or related neutral andcompatible solvents. This rinse practice, albeit a cost increase, willreduce the effects of metal attack to adjacent metals due to a pH-dropduring water mixing with constituents of the stripper. Due tocompatibility issues, wastes from the use of hydrocarbon-based strippersmust be segregated from normal organic streams in a microelectronic fab.

While it is important to give attention to the challenges of polymer andresidue removal from the standpoint of the stripper chemistry, equaldiligence is necessary towards the design of the process and properperformance of the tool. It is generally understood that the primarypurpose of the cleaning tool is to provide control in the process.Variability between part batches is reduced by the operation of thetool. Barring any mixing or chemical adjustments made by the unit, thevariables available to the tool for control include temperature,agitation, and time. With an ever-present intensive pressure to increasethroughput in a manufacturing line, a constant emphasis is to decreasethe process time. Again, without a change in chemistry, this leaves asthe only option to increase temperature and agitation, with theexpectation that polymer dissolution rates will increase resulting inshorter process time. However, other reactions which are contradictoryto the objectives of the process, such as corrosion rate, will alsoincrease with increase in temperature and agitation. Additionally, andmost important, there is continued loading of the stripper chemistrywith the organic substance, causing a reduction in bath life andaccelerates the observation of residue or other phenomena that indicatea drop in performance.

On the temperature continuum, bath life may be facilitated by increasingtemperature or agitation. Where agitation must be controlled to protectsubstrate features, bath life conditions may be increased throughincreased polymer dissolution with increasing temperature. There is afundamental safety limit as communicated by industry guidelines (SEMIS3-91, Safety Guidelines for Heated Chemical Baths). In accordance withSEMI, liquid over temperature shall be controlled at not more than 10degrees C. above the normal operating temperature of the liquid, wherethe typical operating temperature does not exceed the flashpoint of theliquid. Many companies will set policy which is more restrictive such asoperating at 10 degrees C. below the flashpoint and setting the overtemperature to be the flashpoint. These criteria and others may best beobserved in the processing of flat panel displays (FPDs).

Resist stripping at a FPD manufacturing plant occurs on large substratestraveling on a conveyor from one chamber to another. The resist isstripped from the panel by a stripper delivered by a sprayer that floodsthe entire glass surface, traveling to a rinse stage where distilled,deionized, or demineralized water or an alternative solvent is sprayedonto the surface, and the process is completed with a drying step thatincludes a hot air knife. Stripping is supported by at least two producttanks which are separate and distinct and arranged in-line with the flowdirection of the parts. Substrates entering the tool will be first“washed” by the chemistry in the first tank. The stripper is sprayedonto the substrate surface, and upon reacting with the resist andflowing off of the substrate, it is collected and returned to the tankwhere it is subsequently heated and filtered such that any suspended andundissolved materials are removed from the bulk chemistry. The filteredand heated stripper is then cycled back to the spray chamber where it isdelivered to the substrate in a continuous manner that optimizes theresist stripping process.

As the part travels on the conveyor from the first chamber supported bytank #1 to the next chamber supported by tank #2, there is a fundamentalpurity change in the stripper. Although the conditions of operation fortank #2 may be the same as that for tank #1, the amount of resistpresent is lower than that for tank #1. Typical processing times aredefined for chamber #1 to offer a dwell time of the chemistry in contactwith the resist which optimizes resist stripping and maximum removal.Over time, tank #1 will reach a maximum loading capacity for dissolvedresist and a decision to replace the contents will be necessary. Whenthis occurs, the contents of tank #1 will be sent to waste and replacedby the contents of tank #2. The contents of tank #2 will be replacedwith fresh stripper (i.e. pure stripper). In this manner, the system issaid to operate in a counter-current fashion. Namely, the process flowof parts is “counter” or opposite to the flow direction of thechemistry. By using this practice, tanks #1 & #2 become the dirty andclean tanks, respectively. In other words, the unwanted resist isconcentrated in the front of the line while the cleanest chemistriesremain near the end whereby after this point, the product substrate isrinsed and dried.

The configuration given here for the FPD example is consistent withmost, if not all, in-line bench style tools and with many batchstyle-processing tools. In a bench tool, parts move from one station toanother while the tanks are at fixed locations. In a batch style tool,the parts may rotate but remain at a fixed location, while the chemistryis being delivered by spraying. There will be two tanks, the tool willpump from one or the other and carry-out counter-current cleaningdesigns by the use of “dirty” and “clean” tanks.

There is an equal, yet unsatisfied, need to achieve selectivity duringprocessing with these formulated strippers. Namely, as the use of moreaggressive chemistries is put into practice to achieve a desiredcleaning performance in ever reducing time, this practice must be metwithout damage to sensitive metals and the underlying substrate. This isespecially challenging as many of the acids or alkalis of choice willrapidly “spike” the pH of the system, once they are mixed with waterduring the rinse step, causing galvanic corrosion to substrate metals.During the rinse stage on a FPD line, water is sprayed on the heatedglass surface that contains residual stripper. No surfactants are usedin a FPD line, in fear that a foam condition will occur and ultimatelycause catastrophic failing of filters, pumping of dry air bubbles, andworse, contaminating the fab by overflowing stripper which may triggerelectrical shorting and lead to a fire. Since no surfactants are used,there is irregular diffusion due to rising surface tension from theorganic stripper to the aqueous condition. Irregular mixing andspreading cause momentary dead spots on the panel, which contribute toaccelerated corrosion. The corrosive byproduct and foaming condition maybe avoided through rinsing with neutral solvents such as isopropanol(IPA). Although this practice is accepted by several FPD manufacturers,it is both expensive and a flammability hazard.

There is a need, accordingly, for improved stripping compositions whichwill remove the processed resist in a rapid manner while maintainingsafety towards the underlying metallurgy during rinsing with distilled,deionized, or demineralized water, and preventing corroding, gouging,dissolving, dulling, or otherwise marring the surfaces throughout theentire process. Further, growing initiatives exist within the industryto move towards being “green.” A green process and the associatedchemistries are those which will reduce or eliminate the use andgeneration of hazardous substances. According to the American ChemicalSociety's Green Chemistry Institute, there are twelve (12) principleswhich help to define a green chemistry.

This review of polymeric substances in microelectronic fabricationpresents serious and compelling challenges in the industry. Whereorganic dielectrics are used, there is a continuing need for processesand compositions which may be used to effectively re-work a curedpolymer by dissolving and cleaning the unwanted material from theunderlying substrate. In cases of positive photoresists, there is asimilar and continuing need for processes and compositions toeffectively remove polymer from a substrate without deleterious effectsto adjacent metal features. Finally, in the case of negative-tonephotoresists, the same need exists for processes and compositions toeffectively remove polymer from a substrate without deleterious effectsto adjacent metal features. Although all of these materials are organicin origin, their chemistry is different and presents unique challengesthat must be overcome in order to effect the desired cleaning result.

While there is a desire to address the removal needs of organicsubstances with unique compositions, there also, is a challenge todesign a process that is supported by a tool which will enable rapidprocessing of parts, rinsing with water, without deleterious effects tothe substrate. There is a continuing emphasis for the microelectronicsindustry to be green through improving the safety of operations,reducing the use of chemistry, and reducing the generation of hazardouswaste. Taking these challenges together, there is a pressing need toprovide a consistent and universal process, which uses compositions ofmatter that vary depending upon the performance needs of the uniquepolymer or residue to be removed, which provides high performance, highthroughput, a green process, all at a reduced cost of ownership.

SUMMARY OF THE INVENTION

A first embodiment of the present invention concerns a composition forcleaning organic resin from inorganic substrates consisting of a solventor mixture of solvents; and at least one sulfonated polyester at aweight % of greater than 10%, wherein the solvent is selected from thegroup consisting of diethylene glycol, diethylene glycol monoethylether, diethylene glycol monomethyl ether, diethylene glycol monobutylether, diethylene glycol monopropyl ether and mixtures thereof.

Another embodiment concerns a composition for removing organic resinfrom inorganic substrates comprising, an organic solvent or mixture ofsolvents at a weight % of from about 0.5% to about 99.0%, and at leastone water soluble, water dispersible or water dissipatable polyester atweight % of from about 0.5% to about 99.0% Component B, and at least oneadditive which enhances cleaning performance at a weight % of from about0.01% to about 99.0%.

Still another embodiment concerns a method for removing organic resinfrom inorganic substrates comprising, (a) coating said organic resinwith a composition comprising: i) an organic solvent or mixture ofsolvents at a weight % of from about 0.5% to about 99.0%, and ii) atleast one water soluble, water dispersible or water dissipatable polymerat weight % of from about 0.5% to about 99.0% Component B, (b) heatingthe substrate to a temperature and for a time sufficient to achievedissolution of the organic resin, and (c) rinsing the substrate with avolume of a rinsing agent sufficient to remove the composition and theorganic resin

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides stripping compositions and methods, whichquickly and effectively remove polymeric organic substances frominorganic substrates, from metallic, non-metallic and metallizednon-metallic substrates. The stripping composition comprises an organicsolvent, a water-soluble polymer and optionally various additives, whicheffectively removes organic substances and their residues ofthermoplastic or thermoset nature that comprise the basis forfabricating microcircuits in electronic manufacturing. The additive(s)enhance or improve the cleaning performance of the strippingcomposition. The method defines a practice of coating the compositiononto the substrate, heating the substrate to a specific temperature fora given time sufficient to achieve dissolution of the organic substance,and finishing with removal of the by-product by rinsing. The compositionand method work together to provide performance and other desired goalsin manufacturing not normally seen in conventional stripper processes.Although the organic substances to be removed may be cured to a hard andchemically resistant framework when exposed to the customer's process,the invention is found to maintain acceptable performance.

Whenever the term “water-dissipatable” or “water-dispersible” is used inthis description, it will be understood to refer to the activity of awater or aqueous solution on the monomer (Component B). The term isspecifically intended to cover those situations wherein a water oraqueous solution dissolves and/or disperses the monomer material thereinand/or therethrough.

The terms “stripping”, “removing”, and “cleaning” are usedinterchangeably throughout this specification. Likewise, the terms“stripper”, “remover”, and “cleaning composition” are usedinterchangeably. The term “coating” is defined as a method for applyinga film to a substrate such as spray coating, puddle coating, slitcoating or immersing. The terms “film” or “coating” are usedinterchangeably. The indefinite articles “a” and “an” are intended toinclude both the singular and the plural. All ranges are inclusive andcombinable in any order except where it is clear that such numericalranges are constrained to add up to 100%. The term “wt %” means weightpercent based on the total weight of the components of the strippingcomposition, unless otherwise indicated.

A process according to the present invention can involve submerging theinorganic substrate in a bath of the composition according to thepresent invention or preferably by applying the composition as a coatingto the inorganic substrate. Once the substrate is submerged in thecomposition or the composition is applied and covers, or coats, theentire area, heating of the substrate begins. A rapid rate of heatingoccurs until the desired temperature is reached and is held for adesired period of time. Alternatively, the bath into which the substrateis submerged could be maintained at the desired temperature. Rinsingwith a rinsing agent occurs and is followed by a drying step. The totalmethod of practice involves three (3) distinct steps, namely, thecoating, heating, and rinsing. As used herein, the term “rinsing agent”includes any solvent which removes the composition and material to bestripped. Examples of stripping agents include water, acetone, isopropylalcohol and mixtures thereof.

An embodiment of the invention concerns a method whereby a compositionof the present invention is applied as a liquid coating in directcontact with the substance to be removed. The method includes heatinganywhere from approximately 25° C. to about 400° C. or from about 100°C. to about 250° C. Variability in temperature will depend upon thenature and thickness of the organic substance. The heating step processtime can be from about 5 seconds to about 10 minutes, from about 10seconds to about 8 minutes, or even from about 30 seconds to about 4minutes. Moreover, the entire process time can vary anywhere from <15seconds to 180 seconds, in some cases, to 5 minutes to 10 minutes. Thevariability in time is dependent upon the material to be removed, itsthickness, and exposure condition. For example, for a PHost or Novolacresin, the heating step could be from about 15 seconds to about 1minute. However, for other, more highly cured resins, the heating stepcan last from about 2 to 4 minutes or even longer. Once the diffusion ofthe organic substance is complete, rinsing with a rinsing agent such asdistilled, deionized, or demineralized water may be performed.

Rinsing is facilitated by the presence of the water-soluble polymer inthe composition. This polymer performs as a carrier system for theorganic substance to be removed from the inorganic substrate. Therinsing agent used for rinsing can be at a temperature of about 5° C. toabout 100° C. However, rinsing can also occur at room temperature andperforms two objectives, to remove the dissolved organic substance, andto reduce the temperature of the substrate such that next stage normaltool handling may proceed.

Compositions of matter used in this invention include a major componentto be a solvent system of the varieties which include one or more estersselected from the group consisting of structures (I) R—CO₂R₁, glycolether esters of structures (II) R₂—CO₂C₂H₄(OC₂H₄)_(n)—OR₃, (III)R₄—CO₂C₃H₆(OC₃H₆)_(n)—OR₅ and (IV) R₆OCO₂R₇, alcohols selected fromstructures (V) R₈OH, (VI) R₉OC₂H₄(OC₂H₄)_(n)OH, (VII)R₁₀OC₃H₆(OC₃H₆)_(n)OH, (VIII) R₁₁(OC₂H₄)_(n)OH, and (IX)R₁₂(OC₃H₆)_(n)OH, ketones selected from structures (X) R₁₃COR₁₄,sulfoxides selected from structure (XI) R₁₅SOR₁₆, and amides such asN,N-dimethyl formamide, N,N-dimethyl acetamide, and N-methylpyrolidone,wherein R, R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀, R₁₁, R₁₂, R₁₃, R₁₄,R₁₅, and R₁₆ are independently selected from hydrogen or C₁-C₁₄-alkylgroups and n represents a repeating unit ranging from 1 to 10. Further,suitable solvents include, but are not limited to ketones such ascyclohexanone, 2-heptanone, methyl propyl ketone, and methyl amylketone, esters such as isopropyl acetate, ethyl acetate, butyl acetate,ethyl propionate, methyl propionate, gamma-butyrolactone (BLO), ethyl2-hydroxypropionate (ethyl lactate (EL)), ethyl 2-hydroxy-2-methylpropionate, ethyl hydroxyacetate, ethyl 2-hydroxy-3-methyl butanoate,methyl 3-methoxypropionate, ethyl 3-methoxy propionate, ethyl3-ethoxypropionate, methyl 3-ethoxy propionate, methyl pyruvate, andethyl pyruvate, ethers and glycol ethers such as diisopropyl ether,ethyleneglycol monomethyl ether, ethyleneglycol monoethyl ether, andpropylene glycol monomethyl ether (PGME), glycol ether esters such asethyleneglycol monoethyl ether acetate, propyleneglycol methyl etheracetate (PGMEA), and propyleneglycol propyl ether acetate, aromaticsolvents such as methylbenzene, dimethylbenzene, anisole, andnitrobenzene, amide solvents such as N,N-dimethylacetamide (DMAC),N,N-dimethylformamide, and N-methylformanilide, and pyrrolidones such asN-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), dimethylpiperidone,2-pyrrole, N-hydroxyethyl-2-pyrrolidone (HEP),N-cyclohexyl-2-pyrrolidone (CHP), and sulfur containing solvents such asdimethyl sulfoxide, dimethyl sulfone and tetramethylene sulfone.Although these organic solvents may be used either individually or incombination (i.e., as mixtures with others), the preferred solventsystem should contain diethylene glycol (DEG, Eastman Chemical Company),diethylene glycol monoethyl ether (DE Solvent, Eastman ChemicalCompany), and diethylene glycol monopropyl ether (DP Solvent, EastmanChemical Company).

An embodiment of the composition includes of one or more of these saidsolvents at about 0.5 weight percent to about 99.5 weight percent. Inone embodiment, the solvent is present in the solvent composition at aweight % of from about 40% to about 97% or at a weight % of from about60% to about 90%.

The composition also contains a polymer, which exhibits the property ofwater solubility, water dispersibility, or water dissipatability presentat about 0.5 to about 99.5 weight percent and derived from, but notlimited to, alcohol ethoxylates, bisphenol ethoxylates and propoxylates,alkylbenzene salts, cellulose acetate phthalate, cellulosic derivativesof alkoxyethyl and hydroxypropyl, copolymers of ethylene and propyleneoxide, dendritic polyesters, ethoxylated amines, ethoxylated alcoholsalts, ethylene acrylic acid, hydroxy-methacrylates, phosphate esters,polyethylene glycols, polyethylene imine, polyethylene oxides, polyvinylalcohol, polyvinyl pyrollidinone, starch, styrene maleic anhydride,sulfonated acrylics, sulfonated polystyrenes, sulfopolyester of thelinear or branched formula, or rosin acids. The composition includes oneor more of these polymers at about 10.0 weight percent to about 99.5weight percent. In one embodiment, the polymer is present in the solventcomposition at a weight % of from about 12.0 to about 60.0 or at aweight % of from about 15.0 to about 30.0.

In an embodiment, the water soluble polymer includes one or moresulfonated polyesters (sulfopolyesters) of the linear or branchedvarieties respectively, or mixtures thereof. The sulfopolyester iscomprised of

-   -   (i) monomer residues of at least one dicarboxylic acid; and    -   (ii) about 4 to 25 mole percent, based on the total of all acid        and hydroxyl equivalents, of monomer residues of at least one        difunctional sulfomonomer containing at least one metal        sulfonate group bonded to an aromatic ring, wherein the        functional groups are hydroxy or carboxyl or amino and the metal        of the sulfonate group is Na, Li, K, Mg, Ca, Cu, Ni, Fe and        mixtures thereof; and optionally    -   (iii) monomer residues of at least one poly(alkyene glycol)        having the formula

—(OCH₂CH₂)_(n)—

-   -   wherein n is 2 to about 500, provided that the mole percent of        such residues in inversely proportional to the value of n; and    -   (iv) up to about 75 mole percent of monomer residues of at least        one diol, wherein said diol is other than a poly(alkylene        glycol).

Suitable sulfopolyester polymers for use in this invention are thoseknown as Eastman AQ® polymers and Eastman AQ Copolyesters. In general,suitable polymers are such polymers prepared fromdimethyl-5-sodiosulfoisophthalate and its parent acid and salts, whichmay be derived from such co-monomers as isophthalic acid, terephthalicacid, and their esters. Diols commonly used with such acid co-monomersare diethylene glycol, ethylene glycol, triethylene glycol, polyethyleneglycol, propylene glycol, 2-methyl propane diol, neopentyl glycol,1,6-hexanediol, and the like.

The polymer can be selected from water soluble, water dispersible orwater-dissipating sulfopolyesters or polyesteramides (herein afterreferred to collectively as sulfopolyesters) containing ether groups andsulfonate groups having a glycol residue and a dicarboxylic acid residueand at least one difunctional comonomer containing a sulfonate groupattached to an aromatic nucleus and in the form of a metallic salt. Suchpolymers are well known to those skilled in the art and are availablefrom Eastman Chemical Company under the tradename of Eastman AQpolymers. In particular, such sulfopolyesters can be dissolved,dispersed or otherwise dissipated in aqueous dispersions, preferably attemperatures of less than about 80° C. Such polyesters are described ingreater detail in U.S. Pat. No. 3,734,874 the disclosure of which isincorporated herein by reference. One skilled in the art will understandthat the term “residue” or “component” as used in the specification andconcluding claims, refers to the moiety that is the resulting product ofthe chemical species in a particular reaction scheme or subsequentformulation or chemical product, regardless of whether the moiety isactually obtained from the chemical species. Thus, for example, anethylene glycol residue in a polyester refers to one or more —OCH₂CH₂O—repeat units in the polyester, regardless of whether ethylene glycol isused to prepare the polyester.

The aforedescribed polyester material is prepared according to thepolyester preparation technology described in U.S. Pat. Nos. 3,734,874;3,779,993; 3,828,010, 4,233,196, 5,006,598, 5,543,488, 5,552,511,5,552,495, 5,571,876, 5,605,764, 5,709,940, 6,007,749 and 6,162,890 thedisclosures of which are incorporated herein by reference, and the useof the term “acid” in the above description and in the appended claimsincludes the various ester forming or condensable derivatives of theacid reactants such as the dimethyl esters thereof as employed in thepreparations set out in these patents. Examples of sulfo-monomers arethose wherein the sulfonate group is attached to an aromatic nucleussuch as benzene, naphthalene, biphenyl, or the like, or wherein thenucleus is cycloaliphatic such as in 1,4-cyclohexanedicarboxylic acid.

Additives to the composition may comprise about 100 parts-per-million(ppm) to about 99 weight percent of an alkali or acid of organic orinorganic origin to include ammonium hydroxide, quaternary hydroxidessuch as tetramethyl ammonium hydroxide (TMAH), tetraethyl ammoniumhydroxide (TEAH), and benzyltrimethyl ammonium hydroxide (BTMAH), aminessuch as triethylene tetramine, alkanolamines which includemonoethanolamine, monoisopropanolamine, diglycolamine, elementalhydroxides, or alkoxides such as potassium tertiary butyl hydroxide(KTB), alkyl-sulfonic acids such as methanesulfonic (MSA),Toluenesulfonic (TSA), and dodecylbenzene sulfonic acid (DDBSA), formicacid, fatty acids, sulfuric acid, nitric acid, or phosphoric acids. Theadditive can be present in an amount of from about 0.1 weight percent toabout 60 weight percent, about 1.0 weight percent to about 50 weightpercent, or about 5 weight percent to about 40 percent.

In an embodiment, the cleaning composition includes an organic solventor mixture of solvents at a weight % of from about 0.5% to about 99.0%,at least one sulfonated polyester at weight % of from about 0.5% toabout 99.0%, and at least one additive which enhances cleaningperformance at a weight % of from about 0.01% to about 99.0%. Moreover,the solvent is selected from the group consisting of ethylene glycol,diethylene glycol, propylene glycol, diethylene glycol ethyl ether,diethylene glycol methyl ether, diethylene glycol butyl ether,diethylene glycol propyl ether, ethylene glycol propyl ether, ethyleneglycol butyl ether and mixtures thereof.

In another embodiment, the cleaning composition includes the solvent ata weight % of from about 30% to about 95%, the polymer at a weight % offrom about 3% to about 60%, and the additive at a weight % of from about2% to about 60%.

The composition may also include an inhibitor which acts as a protectingagent for substrate composition. The inhibitors include chelating,complexing, or reducing agents, comprising one or more of the knownvarieties, including benzylic hydroxides such as catechol, triazoles,imidazoles, borates, phosphates, and alkyl or elemental silicates, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid,nitrilotriacetic acid, and 2,4-pentanedione, reducing sugars,hydroquinones, glyoxal, salicylaldehyde, fatty acids such as citric andascorbic acid, hydroxylamines, or vanillin.

The compositions according to the present invention may also include asurfactant including one or more of the known varieties, includingnonionic nonyl-phenols and nonyl-ethoxylates, anionic forms that includealkyl-sulfonates, phosphate esters, and succinates, and fluorinatedsystems.

Contact is made to the substrate by the composition via bath submersionor using a coating practice. In microelectronic manufacturing, spincoating is the method of choice used to apply coatings to a substrate.However, other methods exist to include spray-spin coating and slitcoating for large substrates as in FPD manufacturing. In all cases, theobjective is to apply the composition in a manner to achieve completecoverage. Normally, most coating applications are concerned with a highdegree of uniformity. In this invention method, a minimum thicknessshall be established, typically on the order of a minimum value of 1000microns (1 um=1×10⁻⁶ m), but some cases where the organic substance isvery thin, the composition thickness may be smaller. In one embodimentof the present invention, the coating can be up to about 800 micronsthick, between about 200 to about 600 microns thick, or from about 300to about 400 microns thick.

Common practice for spin-coating the composition for this inventionmethod is to dispense the material at the center of a substrate, andoperate the equipment at a low rate of circular motion speed (i.e. <100revolutions per min, rpm). Liquid delivery may be done by a staticmethod, whereby the fluid will “puddle” onto the surface. A dynamicmethod may also be used where the material is dispensed when thesubstrate is already in motion. During the early stages for a newprocess set-up, the exact conditions of rpm and time may need to beestablished in such a manner to ensure complete coverage of thesubstrate with minimal or no waste. There is no need to be concernedwith edge bead formation as this condition will be irrelevant to theprocess objective.

The manipulation of spin-speed is a common focus of many apparatus usedin the microelectronics industry. Substrate rotation will have a directaffect on these properties and produce different coating results. At lowspin-speeds, fluid mobility will be low with minor material loss,however, irregularities in substrate coverage may also occur.Alternatively, high spin-speeds will result in high mobility and highmaterial loss. Although spin-coating is a standard practice in theindustry, experience shows that thick coatings of acceptable thicknessuniformity may be achieved with a spray-coating practice. Once thecoating is completed, heat activation of the process may immediatelyproceed.

Heat application may be conducted through several paths. For manualoperations, a simple hot-plate may be used. This requires the substrateto be moved from one location to another. In situations where automationis of interest, the wafer may remain stationary while heat is appliedusing a base-chuck or an overhead IR convection source. Exact ergonomicsand logistic concerns with respect to controls and throughput can bereadily determined by those skilled in the art of tool design. Once theproper heating regime is followed, the composition and organic resin maybe removed by rinsing with a rinsing agent either in an agitated batchor by direct spray contact.

The stripping compositions of the invention function by maintaining asolvency environment when used on amorphous organic substances such aspositive-tone photoresists of the PHost or novolac varieties. In suchcases and when exposure conditions include moderate temperatures up to150 degrees C., a composition which contains the minimum constituents,including the solvent system and water soluble polymer, is coated andprocessed at the conditions of the invention method. When heated to asufficient temperature, rapid dissolution occurs and diffusion of thephotoresist into the composition proceeds rapidly to completion.Additives such as an alkali agent, inhibitor, and surfactant may be usedto facilitate good results with highly baked (i.e. >150 degrees C.)photoresists. Advantages in using additives contained within thestripping composition may include improved dissolution rates due tosaponifying cross linked photoresist while the inhibitors protectexposed metal during the stripping and rinsing steps.

Organic alkanolamine compounds are preferred for alkaline saponifyingand emulsification of the positive-tone photoresists, to include one ormore low molecular weight candidates, for example, monoethanolamine(MEA), monoisopropanolamine (MIPA), or diglycolamine (DGA), andcombinations thereof. In cases where a negative-tone acrylic photoresistor a cured thermoset polyimide are the candidates to be removed, thecomposition will require a strong alkali, namely, a quaternaryhydroxide, metal hydroxide, or alkoxide.

Similar to the review given here for removing coatings and residues frompositive and negative acrylic, as well as polyimide, compositions alsoapply for removal of negative isoprene (rubber) resist andnegative-epoxy (SU-8™) photoresist. As we have determined for thepositive photoresist and negative acrylic and polyimide, the choice incomposition is dependent upon the material to remove. Fornegative-isoprene, the chemistry is hydrophobic (non-polar) and thecross linked rubber system does not respond to alkalis, only acids.Rubber photoresists require aromatic solvents and hydrophobic acids,such as dodecylbenzene sulfonic acid. For negative epoxy photorest, thechemistry is hydrophilic (polar) and like the rubber photoresists, thesesystems also do not respond to alkalis. The preferred system is onewhich incorporates hydrophilic acids such as methanesulfonic acid (MSA)or sulfuric acid. These systems all contain the water soluble polymer,to facilitate proper rinsing following dissolution of the photoresist.

ExampleS

The following examples further illustrate the present invention. Allpercentages given are by weight unless otherwise specified.

The invention is further illustrated, without limitation, by thefollowing examples. In the first three examples, the measurement ofperformance and selectivity of the invention is conducted usingpractices readily accepted by the industry. In such cases, measurementis made by optical microscope and where necessary, the use of etch ratedeterminations by high sensitivity gravimetric reviews on metallicsubstrates, and where necessary, more detailed studies were conductedusing scanning electron microscopy (SEM). In the following examples,silicon wafers were used as the inorganic substrate upon which theorganic substance is applied and cured. The following items in Table 1represent the organic substances to be removed, their preparationmethods, and the sources from which they were procured.

TABLE 1 List of Organic Resins Used to Demonstrate the Invention.Example # Material Form Type Description/Manufacturer 1 PHost Solidresin Amorphous, Equal quantities as 1:1 worked up positive w/wwt % PB5and PB5W as liquid resin (Hydrite Chemical Co., Brookfield WI),dissolved in PGMEA* as 20 wt % solids 2 Novolac Solid resin Amorphous,Equal quantities as 1:1 worked up positive w/wwt % Rezicure as liquid5200 and 3100 (SI Group, Schenectady, NY), dissolved in PGMEA* as 20 wt% solids 3 Acrylic Dry-film Thermoset, Shipley GA-series negative(GA-20) removed and applied direct, (Rhom & Haas, Inc. Marlborough, MA)4 Polyimide Liquid Thermoset, PI-2611 (HD Non- Microsystems, photoactiveParlin, NJ) 5 Isoprene Liquid Thermoset, SC-Resist (Fujifilm negativeElectronic Materials, North Kingston, RI) *PGMEA: propylene glycolmonomethyl ether acetate

Where applicable, the organic substance is applied in the manner of acoating utilizing a Brewer Science, Inc. CB-100 coater and followingstandard protocol for applying the liquid form of the polymer materialto the inorganic substrate. Once the material is coated, it is sent to asoft bake step for a short 60 sec hot plate bake at 100 degrees C. Fornegative Acrylic resist, the material is exposed to ultraviolet light ofa broad-band type emitting at 365 nm and of a high exposure dose of0.12W/cm2-sec, for an excessive period of 30 min. Following exposure,the wafer was post-exposure baked at a predetermined hard baketemperature and time depending on the resist. Once the wafer sampleshave been prepared, they are staged for experimentation. The experimentsin Examples 2-6 are all conducted identical to each other using the samewafers and handling practices. Each wafer is staged in the work stationwhere the invention will be demonstrated. Compositions are preparedahead of time and also set aside. The invention method is tested byapplying the composition of interest to a portion of the wafer surface.The wafer is then immediately transferred to a hot plate which has beenpreset at the desired processing temperature. Once the wafer is set ontothe hot plate, a digital timer is started. Once the pre-established 60seconds has expired, the wafer is removed and immediately rinsed withdistilled, deionized, or demineralized water from a wash bottle. Therinsed wafer is observed and set aside to dry. Additional observationsare taken and the results are recorded.

Example 1

In all cases, introduction of the sulfopolyester was obtained by theaddition of a premade stock solution. These stock solutions werecomprised of a hydrophilic solvent (Component A) and a water soluble orwater dispersible or water dissipatable polymer (Component B). Thepolymers chosen were various sulfopolyesters of different glasstransition temperatures and viscosities of both the linear and branchedvarieties. Such polymers are well known to those skilled in the art andare available from Eastman Chemical Company under the tradename ofEastman AQ polymers. In particular, such sulfopolyesters can bedissolved, dispersed or otherwise dissipated in aqueous dispersions,preferably at temperatures of less than about 80° C. Such polyesters aredescribed in greater detail in U.S. Pat. No. 3,734,874 the disclosure ofwhich is incorporated herein by reference. The polyesters considered ascandidates for the invention include, but are not limited to, Eastman AQ38S Polymer, Eastman AQ 48 Ultra Polymer, Eastman AQ 55S Polymer,EastONE S85030 Copolyester, Eastman ES-100 Water-Dispersible Polymer,Eastman AQ 1350 Copolyester, and Eastman AQ 2350 Copolyester. Thesolvents chosen were ethylene glycol, diethylene glycol, triethyleneglycol, propylene glycol, diethylene glycol methyl ether (Eastman DMSolvent), diethylene glycol ethyl ether (Eastman DE Solvent), diethyleneglycol propyl ether (Eastman DP Solvent), diethylene glycol butyl ether(Eastman DB Solvent), ethylene glycol propyl ether (Eastman EP Solvent),and ethylene glycol butyl ether (Eastman EB Solvent). In a screeningstudy, solutions were attempted for each of the polymer and solventpairings at 10, 20, and 30 wt % solids. In addition, solutions ofEastman AQ 38S Polymer and Eastman AQ 48 Ultra Polymer each at 40 wt %solids were attempted in the four Diethylene glycol ether solvents.These stock solutions were prepared by adding the solvent to around-bottomed flask with an agitator, condenser, and nitrogen sourceconnected. The appropriate amount of the solid sulfopolyester was thenadded, and the mixture was heated with agitation until the solution wasobtained. Depending on the polymer and solvent pairing and the solidsloading, the solutions were heated to different temperatures for varioustimes ranging from 90 degrees C. for 30 minutes to 180 degrees C. for 70minutes. Table 2 below summarizes these stock solutions. “SuitableSolutions” are those in which the polyester dissolved readily underpreparation conditions, remained soluble on cooling, and the solutionwas suitable for making a coating. “Bad Solutions” are those in whicheither the solids were insoluble in the solvents under the preparationconditions or the solution formed was unstable in the short term.“Disqualified Solutions” are those in which a solution of the samepolymer and solvent paring had previously formed a bad solution at alower solids loading. “Questionable Solutions” are those in which thesolutions formed were either extremely viscous or exhibited signs ofpotential long-term instability, but might be of value for furtherstudy.

TABLE 2 Summary of Potential Stock Solutions Solution AQ- ES- AQ- AQ-Status AQ-38 AQ-48 55 100 EastONE 1350 2350 Suitable 20 21 3 1 1 18 6Solutions Questionable 0 3 2 1 3 2 1 Solutions Bad 11 8 20 12 17 6 15Solutions Disqualified 3 2 5 16 9 4 8 Solutions Total 34 34 30 30 30 3030 Solutions

Based on this screening study, 82 suitable and questionable solutionswere tested on both PHost and Novolac coated wafers which had in bothcases been cured at 150 degrees C. for 15 minutes. In each case, a smallamount of solution was applied to resin coated wafer, the wafer wasimmediately heated to 100 degrees C. for 60 seconds, then immediatelywashed with a stream of water at ambient temperature. A simple visualobservation was used to evaluate completeness of resin removal. Onlythose blends that were judged to exhibit excellent cleaning performanceby visual examination were deemed as passing. Table 3 summarizes theresults.

TABLE 3 Cleaning of Novolac (N) and PHost (P): (C—Cleaned; F—Failed) Wt% Solid 10% 20% 30% 40% Solvent Sulfopolyester P N P N P N P N EthyleneAQ-1350 C F glycol Ethylene AQ-38 C F C F glycol Ethylene AQ-48 C F C Fglycol Ethylene AQ-55 C C glycol Ethylene EastONE C F glycol EthyleneES-100 C F glycol Diethylene AQ-1350 C F glycol Diethylene AQ-38 C C C Cglycol Diethylene AQ-48 C C C C glycol Diethylene AQ-55 C C glycolPropylene AQ-48 C F glycol Propylene AQ-55 C F glycol DM Solvent AQ-1350C C C F C F DM Solvent AQ-2350 C C C F F F DM Solvent AQ-38 C C C F C FF F DM Solvent AQ-48 C C C C C F C F DE Solvent AQ-1350 C C C F C F DESolvent AQ-2350 C F C F C F DE Solvent AQ-38 C C C C F F C F DE SolventAQ-48 C C C C C F C C DP Solvent AQ-1350 C C C F C C DP Solvent AQ-38 FF C C C C C C DP Solvent AQ-48 C C C C C F F F DB Solvent AQ-1350 C C CF C F DB Solvent AQ-38 C F C C C F DB Solvent AQ-48 C C C C F F EPSolvent AQ-1350 C F C F C C EB Solvent AQ-1350 C C C F C C

The composition comprising diethylene glycol ethyl ether and Eastman AQ48 Ultra Polymer at solids loadings ranging from 10 wt % all the way upto 40 wt % were found to exhibit broad performance cleaning both PHostand Novolac photoresist resin from silicon substrate. In addition, thevarious concentrations of these solutions were extremely stable evenafter several months of storage at room temperature.

Therefore, a composition comprising 20 wt % Eastman AQ 48 and 80 wt %diethylene glycol ethyl ether (Eastman DE Solvent) was selected as thesuitable standard composition to be used in developing additive blendsin order to target more exotic and more difficult to removephotoresists. This stock solution comprised 30% of the final solutionsused to treat wafers in Examples 2-6, yielding 6 wt % sulfopolyester and24 wt % DE Solvent in all of these solutions. The following examples 2-6are to demonstrate how one skilled in the art may approach developmentof a composition according to this invention that is suitable forremoval of an organic residue. Neither the selection of this standardcomposition for further studies nor the specific examples that followare intended to limit the scope of this invention.

In contrast with the over-all success of many compositions containing asulfonated polyester, compositions containing other water soluble,dispersible, or dissipatable polymers did not perform nearly as well. Ingeneral, these other polymers were far less soluble in the chosensolvents. Process conditions for achieving the solutions again varieddepending on the polymer and solvent pairing and the solids loading. Inmost cases, the solutions were heated to a temperature ranging from 120degrees C. for 30 minutes up to 180 degrees C. for 80 minutes; however,the polyvinyl pyrollidone and the dendritic polyester were bothnoticeable exceptions that required far less heating. The results of thesolubility study are tabulated below.

TABLE 4 Summary of Stock Solutions not Containing a Sulfonated PolyesterSolution Status ¹DPE ²AMP ³PVP ⁴SPS ⁵HEC ⁶XSS ⁷PVME ⁸CAP Suitable 0 1 400 0 0 10 8 Solutions Question- 26 0 0 0 0 6 0 13 able Solutions Bad 0 100 11 10 4 2 3 Solutions Dis- 4 19 0 19 20 20 18 6 qualified SolutionsTotal 30 30 40 30 30 30 30 30 Solutions ¹DPE—Dendritic Polyester²AMP—Sulfonated acrylic ³PVP—Polyvinyl pyrollidone ⁴SPS—Sulfonatedpolystyrene ⁵HEC—Hydroxyethyl Cellulose ⁶XSS—Xylene sodium sulfonate⁷PVME—Polyvinyl methyl ether ⁸CAP—Cellulose acetate phthalate

From the suitable and questionable blends prepared, a selection of 49was tested on both PHOST and Novolac photoresist that had been cured at150 degrees C. for 15 minutes. In both cases, a small amount of eachcomposition was applied to the resin coated wafer, heated to 100 degreesC. for 60 seconds, and then immediately rinsed off with de-ionized waterat ambient temperature. A simple visual inspection was subsequentlymade, and only those compositions judged to have excellent cleaningperformance were deemed as passing. In many cases, only the 10 wt %solids blends were tested; however, solutions with up to 40 wt % solidsof the polyvinyl pyrollidone were also tested because that particularpolymer was so soluble in every solvent tested. With the exception ofxylene sodium sulfonate, the results were almost wholly negative, andfurther testing was deemed unnecessary. The results of the performancescreening are summarized below.

TABLE 5 Cleaning of Novolac (N) and PHOST (P): (C—Cleaned; F—Failed) Wt% Solids 10% 20% 30% 40% Solvent Polymer P N P N P N P N Ethylene glycol¹AMP C F Ethylene glycol ²PVP F F F F Diethylene glycol ³DPE C FDiethylene glycol PVP F F F F Diethylene glycol ⁴X55 C C Diethyleneglycol ⁵CAP C F Triethylene glycol PVP F F F F Triethylene glycol XSS CF Triethylene glycol CAP C F Propylene glycol PVP F F F F Propyleneglycol XSS C C DM Solvent PVP F F F F DM Solvent XSS C C DM Solvent⁶PVME F F F F F F DM Solvent CAP F F C F DE Solvent DPE C F DE SolventPVP F F F F DE Solvent XSS C C DE Solvent PVME F F F F F F DE SolventCAP F F DP Solvent DPE F F DP Solvent PVP F F F F DP Solvent XSS C F DPSolvent PVME C F F F DP Solvent CAP F F DB Solvent PVP F F F F DBSolvent PVME C F C F DB Solvent CAP F F EP Solvent DPE F F EP SolventPVP F F F F EP Solvent CAP F F EB Solvent PVP F F F F ¹AMP—Sulfonatedacrylic ²PVP—Polyvinyl pyrollidone ³DPE—Dendritic Polyester ⁴XSS—Xylenesodium sulfonate ⁵CAP—Cellulose acetate phthalate ⁶PVME—Polyvinyl methylether

Very few solutions exhibited success in cleaning both PHOST and Novolacphotoresist, and the few compositions that did have this success werequestionable solutions that were non-ideal for use in this invention. Bycomparison, many compositions containing sulfonated polyesters exhibitedmuch better performance dissolving PHOST and Novolac photoresist. Thecompositions containing sulfonated polyesters were significantlypreferable to those containing any of the other polymers considered, anda single composition from those containing sulfonated polyesters waschosen for future testing.

Example 2

Table 4 contains the results from a cleaning study conducted for PHostresin coated as described in Table 1. Resin was cured for 15 minutes at200 degrees C. All cleaning compositions are comprised of 6 wt %sulfopolyester, 24 wt % DE Solvent, with the remaining 70 wt % beingcomprised of two additives as noted in Table 6. Process temperatures forthe cleaning stage were 100 degrees C., 150 degrees C., and 200 degreesC.

TABLE 6 Cleaning Results for PHost Resin Additive A:B Additive Additivewt % A B Concentrations 100° C. 150° C. 200° C. ¹NMP ²TMAH 65:5  CleanClean Clean  NMP  TMAH 50:20 Clean Clean Clean  NMP ³KTB 65:5  CleanClean Clean  NMP  KTB 50:20 Clean Clean Clean  NMP ⁴MEA 65:5  Clean NotNot Clean Clean  NMP  MEA 50:20 Clean Clean Not Clean  NMP  H₃PO₄ 65:5 Clean Clean Not Clean  NMP  H₃PO₄ 50:20 Clean Clean Clean  NMP ⁵MSA65:5  Clean Clean Clean, some  NMP  MSA 50:20 Clean Clean Clean ⁶DMSO TMAH 65:5  Clean Clean Clean  DMSO  TMAH 50:20 Clean Clean Clean  DMSO KTB 65:5  Clean Clean Clean  DMSO  KTB 50:20 Clean Clean Clean  DMSO MEA 65:5  Clean Clean, Not most Clean  DMSO  MEA 50:20 Clean Clean NotClean  DMSO  H₃PO₄ 65:5  Clean Clean, Clean most  DMSO  H₃PO₄ 50:20Clean Clean Clean  DMSO  MSA 65:5  Clean Clean Not Clean  DMSO  MSA50:20 Clean Clean Clean ¹NMP—N-methyl-2-pyrrolidone²TMAH—Tetramethylammonium hydroxide (20 wt % in propylene glycol)³KTB—Potassium tert-butoxide (20 wt % in propylene glycol)⁴MEA—Monoethanol amine ⁵MSA—Methanesulfonic acid ⁶DMSO—Dimethylsulfoxide

The data in Table 4 suggest that most solutions will perform well indissolving and removing the PHost resin, even at high exposuretemperatures of 200 degrees C. The solutions enriched with higherconcentrations of acid or base additives exhibited improved results. Atboth levels of enrichment, solutions containing MEA did not perform wellremoving PHost cured at high temperatures. The primary conclusion hereis that PHost is relatively easy to process at 60 seconds with theinvention method and compositions.

Example 3

Table 5 contains the results from a cleaning study conducted for Novolacresin coated as described in Table 1. Resin was cured for 15 minutes at200 degrees C. All cleaning compositions were comprised of 6 wt %sulfopolyester, 24 wt % DE Solvent, with the remaining 70 wt % beingcomprised of two additives as noted in Table 7. Process temperatures forthe cleaning stage were 100 degrees C., 150 degrees C., and 200 degreesC.

TABLE 7 Cleaning Results for Novolac Resin Additive A:B AdditiveAdditive wt % A B Concentrations 100° C. 150° C. 200° C. ¹NMP ²TMAH65:5  Clean Not Clean Clean  NMP  TMAH 50:20 Not Clean Clean Clean  NMP³KTB 65:5  Clean Clean Not Clean  NMP  KTB 50:20 Clean Clean Clean  NMP⁴MEA 65:5  Clean Clean Not Clean  NMP  MEA 50:20 Clean Clean Not Clean NMP  H₃PO₄ 65:5  Not Clean Not Clean Clean  NMP  H₃PO₄ 50:20 Not CleanClean Clean  NMP ⁵MSA 65:5  Clean Clean Not Clean  NMP  MSA 50:20 CleanClean Clean ⁶DMSO  TMAH 65:5  Clean Clean Clean  DMSO  TMAH 50:20 CleanClean Clean  DMSO  KTB 65:5  Clean Clean Clean  DMSO  KTB 50:20 CleanClean Clean  DMSO  MEA 65:5  Clean Not Not Clean Clean  DMSO  MEA 50:20Clean Clean Not Clean  DMSO  H₃PO₄ 65:5  Not Clean Not Clean Clean  DMSO H₃PO₄ 50:20 Not Not Not Clean Clean Clean  DMSO  MSA 65:5  Clean NotNot Clean Clean  DMSO  MSA 50:20 Clean Clean Not Clean¹NMP—N-methyl-2-pyrrolidone ²TMAH—Tetramethylammonium hydroxide (20 wt %in propylene glycol) ³KTB—Potassium tert-butoxide (20 wt % in propyleneglycol) ⁴MEA—Monoethanol amine ⁵MSA—Methanesulfonic acid⁶DMSO—Dimethylsulfoxide

Table 5 suggests that most additive combinations are suitable forcleaning cured Novolac resin from silica substrates; however, somedifficulty is encountered when cleaning at 200° C. Acidic solutions donot produce desirable results especially on highly cured novolac resin,with phosphoric acid containing compositions failing in nearly everyattempt.

Example 4

Table 6 contains the results from a cleaning study conducted for acrylicresin coated as described in Table 1. Resin was cured for 15 minutes at150 degrees C. All cleaning compositions were comprised of 6 wt %sulfopolyester, 24 wt % DE Solvent, with the remaining 70 wt % beingcomprised of two additives as noted in Table 8. Process temperatures forthe cleaning stage were 100 degrees C., 150 degrees C., and 200 degreesC. Results are tabulated below.

TABLE 8 Cleaning Results for Acrylic Resin Additive A:B AdditiveAdditive wt % A B Concentrations 100° C. 150° C. 200° C. ¹NMP ²TMAH65:5  Clean Partial Partial Clean Clean  NMP  TMAH 50:20 Clean PartialClean Clean  NMP ³KTB 65:5  Clean Partial Partial Clean Clean  NMP  KTB50:20 Clean Clean Partial Clean  NMP ⁴MEA 65:5  Clean Partial PartialClean Clean  NMP  MEA 50:20 Partial Partial Partial Clean Clean Clean NMP  H₃PO₄ 65:5  Partial Partial Partial Clean Clean Clean  NMP  H₃PO₄50:20 Partial Partial No Clean Clean Clean  NMP ⁵MSA 65:5  PartialPartial Partial Clean Clean Clean  NMP  MSA 50:20 Partial PartialPartial Clean Clean Clean ⁶DMSO  TMAH 65:5  Clean Partial Partial CleanClean  DMSO  TMAH 50:20 Clean Partial Clean Clean  DMSO  KTB 65:5  CleanPartial Partial Clean Clean  DMSO  KTB 50:20 Partial Partial PartialClean Clean Clean  DMSO  MEA 65:5  Clean Partial Partial Clean Clean DMSO  MEA 50:20 Clean Partial Partial Clean Clean  DMSO  H₃PO₄ 65:5 Partial Partial Partial Clean Clean Clean  DMSO  H₃PO₄ 50:20 Not Not NotClean Clean Clean  DMSO  MSA 65:5  Partial Partial Partial Clean CleanClean  DMSO  MSA 50:20 Partial Partial Partial Clean Clean Clean¹NMP—N-methyl-2-pyrrolidone ²TMAH—Tetramethylammonium hydroxide (20 wt %in propylene glycol) ³KTB—Potassium tert-butoxide (20 wt % in propyleneglycol) ⁴MEA—Monoethanol amine ⁵MSA—Methanesulfonic acid⁶DMSO—Dimethylsulfoxide

Table 6 suggests that cured acrylic resin is more difficult to cleanthan either PHOST or novolac resin. Only the use of highly basicmaterials such as TMAH, MEA, or KTB in the additive component produceddesirable results on low temperature cleaned wafers.

Example 5

Table 7 contains the results from a cleaning study conducted forPolyimide resin coated as described in Table 1. After the soft bake,wafers were cured for 15 minutes at 200 degrees C. followed by anadditional 30 minutes at 350 degrees C. All cleaning compositions werecomprised of 6 wt % sulfopolyester, 24 wt % DE Solvent, with theremaining 70 wt % being comprised of three additives as noted in Table9. Process temperatures for the cleaning stage were 100 degrees C., 150degrees C., and 200 degrees C. Results are tabulated below.

TABLE 9 Cleaning Results for Polyimide Resin Additive A:B:C Add- Add- wt% itive Additive itive Concen- A B C trations 100° C. 150° C. 200° C.¹NMP DMSO MEA 23.5:23.5:23 Not Not Not clean clean clean NMP DMSO ³KTB23.5:23.5:23 Not Clean Clean clean NMP DMSO ²TMAH 23.5:23.5:23 Not CleanClean clean NMP ⁵Surf ⁴MEA 46:2:22 Not Not Not clean clean clean NMPSurf KTB 46:2:22 Not Clean Clean clean NMP Surf TMAH 46:2:22 Clean CleanClean DMSO None MEA 47:23 Not Not Not clean clean clean DMSO None KTB47:23 Not Not Clean clean clean DMSO None TMAH 47:23 Not Clean Cleanclean DMSO Surf MEA 46:2:22 Not Not Not clean clean clean DMSO Surf KTB46:2:22 Not Clean Clean clean DMSO Surf TMAH 46:2:22 Not Clean Cleanclean DMSO ⁷DMSO₂ ⁸KTB + 27.5:23.5:23 Not Clean Clean MEA clean NMP DMSO⁸KTB + 27.5:23.5:23 Not Clean Clean MEA clean¹NMP—N-methyl-2-pyrrolidone ²TMAH—Tetramethylammonium hydroxide (20 wt %in propylene glycol) ³KTB—Potassium tert-butoxide (20 wt % in propyleneglycol) ⁴MEA—Monoethanol amine ⁵Surf—Nonionic alkyl polyethylene glycolether surfactant ⁶DMSO—Dimethylsulfoxide ⁷DMSO₂—Dimethylsulfone ⁸KTB +MEA—equal weights of 20 wt % potassium t-butoxide in propylene glycoland monoethanol amine

Table 7 suggests that higher process temperatures yield best results forcleaning polyimide resin from inorganic substrates. Virtually no goodresults were observed at a process temperature of 100 degrees C.Additionally, polyimide removal required a strong alkali component witha pKa equal to or greater than 12. In all instances where MEA is presentalone in the composition as the only alkali, cleaning results were notacceptable. The presence of KTB or TMAH did promote good results.

Example 6

Table 8 contains the results from a cleaning study conducted forIsoprene resin coated as described in Table 1. Wafers were cured for 15minutes at 150 degrees C. All cleaning compositions were comprised of 6wt % sulfopolyester, 24 wt % DE Solvent, with 68 wt % being comprised oftwo additives as noted in Table 7 and 2 wt % being comprised of asurfactant such as Zelec™ UN (alkoxyphosphate ester surfactant). Processtemperatures for the cleaning stage were 100 degrees C., 150 degrees C.,and 200 degrees C.

TABLE 10 Cleaning Results for Isoprene Resin Additive A:B AdditiveAdditive wt % A B Concentrations 100° C. 150° C. 200° C. ¹Aromatic 150²DDBSA 41:27 Not Clean Clean Fluid Clean 1-Dodecene  DDBSA 41:27 NotClean Clean Clean ¹Aromatic 150 Fluid from ExxonMobil Chemical²DDBSA—dodecylbenzenesulfonic acid

The cleaning composition presented in Table 10 was designed to besignificantly hydrophobic (hydrocarbon) in order to allow penetration ofthe cleaning composition into the resin. The compositions shown hererepresent a key condition that is necessary to affect properperformance. Elevated temperatures were found necessary to adequatelyremove the rubber-like isoprene photoresist from the inorganic substratein 60 seconds.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

We claim:
 1. A composition for cleaning organic resin from inorganicsubstrates comprising: a solvent or mixture of solvents; and at leastone sulfonated polyester at a weight % of greater than 10.0%, whereinthe solvent is selected from the group consisting of ethylene glycol,diethylene glycol, propylene glycol, diethylene glycol ethyl ether,diethylene glycol methyl ether, diethylene glycol butyl ether,diethylene glycol propyl ether, ethylene glycol propyl ether, ethyleneglycol butyl ether and mixtures thereof.
 2. The composition according toclaim 1, wherein the solvent is at a weight % of from about 40% to about97%.
 3. The composition according to claim 2, wherein the solvent is ata weight % of from about 60% to about 90%.